Removed SDL_HasGamepads(), SDL_HasJoysticks(), and SDL_HasSensors()

Also cleaned up logic for whether we need to poll for events:
- We need to periodically poll for joysticks to handle hotplug.
- We need to frequently poll for joysticks and sensors when they're open so their state can be updated

include/SDL3/SDL_gamepad.h

@@ -274,17 +274,6 @@ extern DECLSPEC char * SDLCALL SDL_GetGamepadMappingForGUID(SDL_JoystickGUID gui
  */
 extern DECLSPEC char * SDLCALL SDL_GetGamepadMapping(SDL_Gamepad *gamepad);
 
-/**
- * Return whether there are gamepads connected
- *
- * \returns SDL_TRUE if there are gamepads connected, SDL_FALSE otherwise.
- *
- * \since This function is available since SDL 3.0.0.
- *
- * \sa SDL_GetGamepads
- */
-extern DECLSPEC SDL_bool SDLCALL SDL_HasGamepads(void);
-
 /**
  * Get a list of currently connected gamepads.
  *